$OpenBSD: patch-lib_sockopt_h,v 1.2 2016/03/22 12:57:54 jca Exp $

Revert 69bf3a39; does not work on at least (Open/Net)BSD.
This can be put back if we get RFC3678 support.

--- lib/sockopt.h.orig	Wed Mar 16 00:17:17 2016
+++ lib/sockopt.h	Mon Mar 21 02:12:14 2016
@@ -85,8 +85,12 @@ extern int setsockopt_ipv6_tclass (int, int);
 
 extern int setsockopt_ipv4_multicast_if(int sock, ifindex_t ifindex);
 extern int setsockopt_ipv4_multicast(int sock, int optname,
+                                     struct in_addr if_addr
+					 /* required: interface to join on */,
                                      unsigned int mcast_addr,
-			             ifindex_t ifindex);
+			             ifindex_t ifindex
+					 /* optional: if non-zero, may be used
+					 	instead of if_addr */);
 extern int setsockopt_ipv4_tos(int sock, int tos);
 
 /* Ask for, and get, ifindex, by whatever method is supported. */
